1) Field of the Invention
This invention relates to a vibration damper for damping the propagation of vibration through solid, which is caused by the vibration of steel panel sheets for vehicles such as cars, covers for machines, etc., and especially, to a vibration damper suitable for use in installing on the floors of vehicles.
2) Description of the Related Art
Vibration dampers of this kind have heretofore been formed of a sheet obtained by mixing an inorganic filler and reinforcing fibers into a base comprising a conventional asphalt, for example, single blown asphalt or straight asphalt, or a mixed asphalt thereof, and a modifier such as a synthetic rubber or an elastomer, which is mixed therewith, said sheet having a high specific gravity.
Such vibration dampers exhibit excellent vibration-damping effect at low temperatures. However, such vibration-damping effect becomes lower as the temperature rises.
Thus, when the temperature of a location wherein the vibration damper is utilized is 40.degree. C. or higher at the time a vehicle is used, the vibration-damping effect is lowered.
For this reason, it is preferable that the vibration damper should be made thicker in order to enhance its vibration-damping properties. However, such a thicker vibration damper is not preferred because the weight of the vehicle is increased when it is installed on the floor of the vehicle. In addition, difficulties are also encountered with regard to the installation work. Accordingly, there is a limit even to the thickening of the vibration damper. This limit has involved a disadvantage in that it is impossible to sufficiently enhance the vibration-damping effect at 20.degree.-60.degree. C.
In addition, it has been known to incorporate a large amount of a filler in a vibration damper of this kind so as to improve its vibration-damping properties. This has been accompanied by a disadvantage that when such a vibration damper is installed on a vehicle floor made of a steel sheet, its adhesion properties to the steel sheet is deteriorated and reliable laying is hence infeasible unless an adhesive is used.